import {
  BufferAttribute,
  BufferGeometry,
  Float32BufferAttribute,
  InterleavedBuffer,
  InterleavedBufferAttribute,
  TriangleFanDrawMode,
  TrianglesDrawMode,
  TriangleStripDrawMode,
  Vector3
} from '../../three.module.js';


function computeTangents(geometry) {

  geometry.computeTangents();
  console.warn('THREE.BufferGeometryUtils: .computeTangents() has been removed. Use BufferGeometry.computeTangents() instead.');

}

/**
 * @param  {Array<BufferGeometry>} geometries
 * @param  {Boolean} useGroups
 * @return {BufferGeometry}
 */
function mergeBufferGeometries(geometries, useGroups = false) {

  const isIndexed = geometries[0].index !== null;

  const attributesUsed = new Set(Object.keys(geometries[0].attributes));
  const morphAttributesUsed = new Set(Object.keys(geometries[0].morphAttributes));

  const attributes = {};
  const morphAttributes = {};

  const morphTargetsRelative = geometries[0].morphTargetsRelative;

  const mergedGeometry = new BufferGeometry();

  let offset = 0;

  for (let i = 0; i < geometries.length; ++i) {

    const geometry = geometries[i];
    let attributesCount = 0;

    // ensure that all geometries are indexed, or none

    if (isIndexed !== (geometry.index !== null)) {

      console.error('THREE.BufferGeometryUtils: .mergeBufferGeometries() failed with geometry at index ' + i + '. All geometries must have compatible attributes; make sure index attribute exists among all geometries, or in none of them.');
      return null;

    }

    // gather attributes, exit early if they're different

    for (const name in geometry.attributes) {

      if (!attributesUsed.has(name)) {

        console.error('THREE.BufferGeometryUtils: .mergeBufferGeometries() failed with geometry at index ' + i + '. All geometries must have compatible attributes; make sure "' + name + '" attribute exists among all geometries, or in none of them.');
        return null;

      }

      if (attributes[name] === undefined) attributes[name] = [];

      attributes[name].push(geometry.attributes[name]);

      attributesCount++;

    }

    // ensure geometries have the same number of attributes

    if (attributesCount !== attributesUsed.size) {

      console.error('THREE.BufferGeometryUtils: .mergeBufferGeometries() failed with geometry at index ' + i + '. Make sure all geometries have the same number of attributes.');
      return null;

    }

    // gather morph attributes, exit early if they're different

    if (morphTargetsRelative !== geometry.morphTargetsRelative) {

      console.error('THREE.BufferGeometryUtils: .mergeBufferGeometries() failed with geometry at index ' + i + '. .morphTargetsRelative must be consistent throughout all geometries.');
      return null;

    }

    for (const name in geometry.morphAttributes) {

      if (!morphAttributesUsed.has(name)) {

        console.error('THREE.BufferGeometryUtils: .mergeBufferGeometries() failed with geometry at index ' + i + '.  .morphAttributes must be consistent throughout all geometries.');
        return null;

      }

      if (morphAttributes[name] === undefined) morphAttributes[name] = [];

      morphAttributes[name].push(geometry.morphAttributes[name]);

    }

    // gather .userData

    mergedGeometry.userData.mergedUserData = mergedGeometry.userData.mergedUserData || [];
    mergedGeometry.userData.mergedUserData.push(geometry.userData);

    if (useGroups) {

      let count;

      if (isIndexed) {

        count = geometry.index.count;

      } else if (geometry.attributes.position !== undefined) {

        count = geometry.attributes.position.count;

      } else {

        console.error('THREE.BufferGeometryUtils: .mergeBufferGeometries() failed with geometry at index ' + i + '. The geometry must have either an index or a position attribute');
        return null;

      }

      mergedGeometry.addGroup(offset, count, i);

      offset += count;

    }

  }

  // merge indices

  if (isIndexed) {

    let indexOffset = 0;
    const mergedIndex = [];

    for (let i = 0; i < geometries.length; ++i) {

      const index = geometries[i].index;

      for (let j = 0; j < index.count; ++j) {

        mergedIndex.push(index.getX(j) + indexOffset);

      }

      indexOffset += geometries[i].attributes.position.count;

    }

    mergedGeometry.setIndex(mergedIndex);

  }

  // merge attributes

  for (const name in attributes) {

    const mergedAttribute = mergeBufferAttributes(attributes[name]);

    if (!mergedAttribute) {

      console.error('THREE.BufferGeometryUtils: .mergeBufferGeometries() failed while trying to merge the ' + name + ' attribute.');
      return null;

    }

    mergedGeometry.setAttribute(name, mergedAttribute);

  }

  // merge morph attributes

  for (const name in morphAttributes) {

    const numMorphTargets = morphAttributes[name][0].length;

    if (numMorphTargets === 0) break;

    mergedGeometry.morphAttributes = mergedGeometry.morphAttributes || {};
    mergedGeometry.morphAttributes[name] = [];

    for (let i = 0; i < numMorphTargets; ++i) {

      const morphAttributesToMerge = [];

      for (let j = 0; j < morphAttributes[name].length; ++j) {

        morphAttributesToMerge.push(morphAttributes[name][j][i]);

      }

      const mergedMorphAttribute = mergeBufferAttributes(morphAttributesToMerge);

      if (!mergedMorphAttribute) {

        console.error('THREE.BufferGeometryUtils: .mergeBufferGeometries() failed while trying to merge the ' + name + ' morphAttribute.');
        return null;

      }

      mergedGeometry.morphAttributes[name].push(mergedMorphAttribute);

    }

  }

  return mergedGeometry;

}

/**
 * @param {Array<BufferAttribute>} attributes
 * @return {BufferAttribute}
 */
function mergeBufferAttributes(attributes) {

  let TypedArray;
  let itemSize;
  let normalized;
  let arrayLength = 0;

  for (let i = 0; i < attributes.length; ++i) {

    const attribute = attributes[i];

    if (attribute.isInterleavedBufferAttribute) {

      console.error('THREE.BufferGeometryUtils: .mergeBufferAttributes() failed. InterleavedBufferAttributes are not supported.');
      return null;

    }

    if (TypedArray === undefined) TypedArray = attribute.array.constructor;
    if (TypedArray !== attribute.array.constructor) {

      console.error('THREE.BufferGeometryUtils: .mergeBufferAttributes() failed. BufferAttribute.array must be of consistent array types across matching attributes.');
      return null;

    }

    if (itemSize === undefined) itemSize = attribute.itemSize;
    if (itemSize !== attribute.itemSize) {

      console.error('THREE.BufferGeometryUtils: .mergeBufferAttributes() failed. BufferAttribute.itemSize must be consistent across matching attributes.');
      return null;

    }

    if (normalized === undefined) normalized = attribute.normalized;
    if (normalized !== attribute.normalized) {

      console.error('THREE.BufferGeometryUtils: .mergeBufferAttributes() failed. BufferAttribute.normalized must be consistent across matching attributes.');
      return null;

    }

    arrayLength += attribute.array.length;

  }

  const array = new TypedArray(arrayLength);
  let offset = 0;

  for (let i = 0; i < attributes.length; ++i) {

    array.set(attributes[i].array, offset);

    offset += attributes[i].array.length;

  }

  return new BufferAttribute(array, itemSize, normalized);

}

/**
 * @param {Array<BufferAttribute>} attributes
 * @return {Array<InterleavedBufferAttribute>}
 */
function interleaveAttributes(attributes) {

  // Interleaves the provided attributes into an InterleavedBuffer and returns
  // a set of InterleavedBufferAttributes for each attribute
  let TypedArray;
  let arrayLength = 0;
  let stride = 0;

  // calculate the the length and type of the interleavedBuffer
  for (let i = 0, l = attributes.length; i < l; ++i) {

    const attribute = attributes[i];

    if (TypedArray === undefined) TypedArray = attribute.array.constructor;
    if (TypedArray !== attribute.array.constructor) {

      console.error('AttributeBuffers of different types cannot be interleaved');
      return null;

    }

    arrayLength += attribute.array.length;
    stride += attribute.itemSize;

  }

  // Create the set of buffer attributes
  const interleavedBuffer = new InterleavedBuffer(new TypedArray(arrayLength), stride);
  let offset = 0;
  const res = [];
  const getters = ['getX', 'getY', 'getZ', 'getW'];
  const setters = ['setX', 'setY', 'setZ', 'setW'];

  for (let j = 0, l = attributes.length; j < l; j++) {

    const attribute = attributes[j];
    const itemSize = attribute.itemSize;
    const count = attribute.count;
    const iba = new InterleavedBufferAttribute(interleavedBuffer, itemSize, offset, attribute.normalized);
    res.push(iba);

    offset += itemSize;

    // Move the data for each attribute into the new interleavedBuffer
    // at the appropriate offset
    for (let c = 0; c < count; c++) {

      for (let k = 0; k < itemSize; k++) {

        iba[setters[k]](c, attribute[getters[k]](c));

      }

    }

  }

  return res;

}

/**
 * @param {Array<BufferGeometry>} geometry
 * @return {number}
 */
function estimateBytesUsed(geometry) {

  // Return the estimated memory used by this geometry in bytes
  // Calculate using itemSize, count, and BYTES_PER_ELEMENT to account
  // for InterleavedBufferAttributes.
  let mem = 0;
  for (const name in geometry.attributes) {

    const attr = geometry.getAttribute(name);
    mem += attr.count * attr.itemSize * attr.array.BYTES_PER_ELEMENT;

  }

  const indices = geometry.getIndex();
  mem += indices ? indices.count * indices.itemSize * indices.array.BYTES_PER_ELEMENT : 0;
  return mem;

}

/**
 * @param {BufferGeometry} geometry
 * @param {number} tolerance
 * @return {BufferGeometry>}
 */
function mergeVertices(geometry, tolerance = 1e-4) {

  tolerance = Math.max(tolerance, Number.EPSILON);

  // Generate an index buffer if the geometry doesn't have one, or optimize it
  // if it's already available.
  const hashToIndex = {};
  const indices = geometry.getIndex();
  const positions = geometry.getAttribute('position');
  const vertexCount = indices ? indices.count : positions.count;

  // next value for triangle indices
  let nextIndex = 0;

  // attributes and new attribute arrays
  const attributeNames = Object.keys(geometry.attributes);
  const attrArrays = {};
  const morphAttrsArrays = {};
  const newIndices = [];
  const getters = ['getX', 'getY', 'getZ', 'getW'];

  // initialize the arrays
  for (let i = 0, l = attributeNames.length; i < l; i++) {

    const name = attributeNames[i];

    attrArrays[name] = [];

    const morphAttr = geometry.morphAttributes[name];
    if (morphAttr) {

      morphAttrsArrays[name] = new Array(morphAttr.length).fill().map(() => []);

    }

  }

  // convert the error tolerance to an amount of decimal places to truncate to
  const decimalShift = Math.log10(1 / tolerance);
  const shiftMultiplier = Math.pow(10, decimalShift);
  for (let i = 0; i < vertexCount; i++) {

    const index = indices ? indices.getX(i) : i;

    // Generate a hash for the vertex attributes at the current index 'i'
    let hash = '';
    for (let j = 0, l = attributeNames.length; j < l; j++) {

      const name = attributeNames[j];
      const attribute = geometry.getAttribute(name);
      const itemSize = attribute.itemSize;

      for (let k = 0; k < itemSize; k++) {

        // double tilde truncates the decimal value
        hash += `${~~(attribute[getters[k]](index) * shiftMultiplier)},`;

      }

    }

    // Add another reference to the vertex if it's already
    // used by another index
    if (hash in hashToIndex) {

      newIndices.push(hashToIndex[hash]);

    } else {

      // copy data to the new index in the attribute arrays
      for (let j = 0, l = attributeNames.length; j < l; j++) {

        const name = attributeNames[j];
        const attribute = geometry.getAttribute(name);
        const morphAttr = geometry.morphAttributes[name];
        const itemSize = attribute.itemSize;
        const newarray = attrArrays[name];
        const newMorphArrays = morphAttrsArrays[name];

        for (let k = 0; k < itemSize; k++) {

          const getterFunc = getters[k];
          newarray.push(attribute[getterFunc](index));

          if (morphAttr) {

            for (let m = 0, ml = morphAttr.length; m < ml; m++) {

              newMorphArrays[m].push(morphAttr[m][getterFunc](index));

            }

          }

        }

      }

      hashToIndex[hash] = nextIndex;
      newIndices.push(nextIndex);
      nextIndex++;

    }

  }

  // Generate typed arrays from new attribute arrays and update
  // the attributeBuffers
  const result = geometry.clone();
  for (let i = 0, l = attributeNames.length; i < l; i++) {

    const name = attributeNames[i];
    const oldAttribute = geometry.getAttribute(name);

    const buffer = new oldAttribute.array.constructor(attrArrays[name]);
    const attribute = new BufferAttribute(buffer, oldAttribute.itemSize, oldAttribute.normalized);

    result.setAttribute(name, attribute);

    // Update the attribute arrays
    if (name in morphAttrsArrays) {

      for (let j = 0; j < morphAttrsArrays[name].length; j++) {

        const oldMorphAttribute = geometry.morphAttributes[name][j];

        const buffer = new oldMorphAttribute.array.constructor(morphAttrsArrays[name][j]);
        const morphAttribute = new BufferAttribute(buffer, oldMorphAttribute.itemSize, oldMorphAttribute.normalized);
        result.morphAttributes[name][j] = morphAttribute;

      }

    }

  }

  // indices

  result.setIndex(newIndices);

  return result;

}

/**
 * @param {BufferGeometry} geometry
 * @param {number} drawMode
 * @return {BufferGeometry>}
 */
function toTrianglesDrawMode(geometry, drawMode) {

  if (drawMode === TrianglesDrawMode) {

    console.warn('THREE.BufferGeometryUtils.toTrianglesDrawMode(): Geometry already defined as triangles.');
    return geometry;

  }

  if (drawMode === TriangleFanDrawMode || drawMode === TriangleStripDrawMode) {

    let index = geometry.getIndex();

    // generate index if not present

    if (index === null) {

      const indices = [];

      const position = geometry.getAttribute('position');

      if (position !== undefined) {

        for (let i = 0; i < position.count; i++) {

          indices.push(i);

        }

        geometry.setIndex(indices);
        index = geometry.getIndex();

      } else {

        console.error('THREE.BufferGeometryUtils.toTrianglesDrawMode(): Undefined position attribute. Processing not possible.');
        return geometry;

      }

    }

    //

    const numberOfTriangles = index.count - 2;
    const newIndices = [];

    if (drawMode === TriangleFanDrawMode) {

      // gl.TRIANGLE_FAN

      for (let i = 1; i <= numberOfTriangles; i++) {

        newIndices.push(index.getX(0));
        newIndices.push(index.getX(i));
        newIndices.push(index.getX(i + 1));

      }

    } else {

      // gl.TRIANGLE_STRIP

      for (let i = 0; i < numberOfTriangles; i++) {

        if (i % 2 === 0) {

          newIndices.push(index.getX(i));
          newIndices.push(index.getX(i + 1));
          newIndices.push(index.getX(i + 2));

        } else {

          newIndices.push(index.getX(i + 2));
          newIndices.push(index.getX(i + 1));
          newIndices.push(index.getX(i));

        }

      }

    }

    if ((newIndices.length / 3) !== numberOfTriangles) {

      console.error('THREE.BufferGeometryUtils.toTrianglesDrawMode(): Unable to generate correct amount of triangles.');

    }

    // build final geometry

    const newGeometry = geometry.clone();
    newGeometry.setIndex(newIndices);
    newGeometry.clearGroups();

    return newGeometry;

  } else {

    console.error('THREE.BufferGeometryUtils.toTrianglesDrawMode(): Unknown draw mode:', drawMode);
    return geometry;

  }

}

/**
 * Calculates the morphed attributes of a morphed/skinned BufferGeometry.
 * Helpful for Raytracing or Decals.
 * @param {Mesh | Line | Points} object An instance of Mesh, Line or Points.
 * @return {Object} An Object with original position/normal attributes and morphed ones.
 */
function computeMorphedAttributes(object) {

  if (object.geometry.isBufferGeometry !== true) {

    console.error('THREE.BufferGeometryUtils: Geometry is not of type BufferGeometry.');
    return null;

  }

  const _vA = new Vector3();
  const _vB = new Vector3();
  const _vC = new Vector3();

  const _tempA = new Vector3();
  const _tempB = new Vector3();
  const _tempC = new Vector3();

  const _morphA = new Vector3();
  const _morphB = new Vector3();
  const _morphC = new Vector3();

  function _calculateMorphedAttributeData(
    object,
    material,
    attribute,
    morphAttribute,
    morphTargetsRelative,
    a,
    b,
    c,
    modifiedAttributeArray
  ) {

    _vA.fromBufferAttribute(attribute, a);
    _vB.fromBufferAttribute(attribute, b);
    _vC.fromBufferAttribute(attribute, c);

    const morphInfluences = object.morphTargetInfluences;

    if (material.morphTargets && morphAttribute && morphInfluences) {

      _morphA.set(0, 0, 0);
      _morphB.set(0, 0, 0);
      _morphC.set(0, 0, 0);

      for (let i = 0, il = morphAttribute.length; i < il; i++) {

        const influence = morphInfluences[i];
        const morph = morphAttribute[i];

        if (influence === 0) continue;

        _tempA.fromBufferAttribute(morph, a);
        _tempB.fromBufferAttribute(morph, b);
        _tempC.fromBufferAttribute(morph, c);

        if (morphTargetsRelative) {

          _morphA.addScaledVector(_tempA, influence);
          _morphB.addScaledVector(_tempB, influence);
          _morphC.addScaledVector(_tempC, influence);

        } else {

          _morphA.addScaledVector(_tempA.sub(_vA), influence);
          _morphB.addScaledVector(_tempB.sub(_vB), influence);
          _morphC.addScaledVector(_tempC.sub(_vC), influence);

        }

      }

      _vA.add(_morphA);
      _vB.add(_morphB);
      _vC.add(_morphC);

    }

    if (object.isSkinnedMesh) {

      object.boneTransform(a, _vA);
      object.boneTransform(b, _vB);
      object.boneTransform(c, _vC);

    }

    modifiedAttributeArray[a * 3 + 0] = _vA.x;
    modifiedAttributeArray[a * 3 + 1] = _vA.y;
    modifiedAttributeArray[a * 3 + 2] = _vA.z;
    modifiedAttributeArray[b * 3 + 0] = _vB.x;
    modifiedAttributeArray[b * 3 + 1] = _vB.y;
    modifiedAttributeArray[b * 3 + 2] = _vB.z;
    modifiedAttributeArray[c * 3 + 0] = _vC.x;
    modifiedAttributeArray[c * 3 + 1] = _vC.y;
    modifiedAttributeArray[c * 3 + 2] = _vC.z;

  }

  const geometry = object.geometry;
  const material = object.material;

  let a, b, c;
  const index = geometry.index;
  const positionAttribute = geometry.attributes.position;
  const morphPosition = geometry.morphAttributes.position;
  const morphTargetsRelative = geometry.morphTargetsRelative;
  const normalAttribute = geometry.attributes.normal;
  const morphNormal = geometry.morphAttributes.position;

  const groups = geometry.groups;
  const drawRange = geometry.drawRange;
  let i, j, il, jl;
  let group, groupMaterial;
  let start, end;

  const modifiedPosition = new Float32Array(positionAttribute.count * positionAttribute.itemSize);
  const modifiedNormal = new Float32Array(normalAttribute.count * normalAttribute.itemSize);

  if (index !== null) {

    // indexed buffer geometry

    if (Array.isArray(material)) {

      for (i = 0, il = groups.length; i < il; i++) {

        group = groups[i];
        groupMaterial = material[group.materialIndex];

        start = Math.max(group.start, drawRange.start);
        end = Math.min((group.start + group.count), (drawRange.start + drawRange.count));

        for (j = start, jl = end; j < jl; j += 3) {

          a = index.getX(j);
          b = index.getX(j + 1);
          c = index.getX(j + 2);

          _calculateMorphedAttributeData(
            object,
            groupMaterial,
            positionAttribute,
            morphPosition,
            morphTargetsRelative,
            a, b, c,
            modifiedPosition
          );

          _calculateMorphedAttributeData(
            object,
            groupMaterial,
            normalAttribute,
            morphNormal,
            morphTargetsRelative,
            a, b, c,
            modifiedNormal
          );

        }

      }

    } else {

      start = Math.max(0, drawRange.start);
      end = Math.min(index.count, (drawRange.start + drawRange.count));

      for (i = start, il = end; i < il; i += 3) {

        a = index.getX(i);
        b = index.getX(i + 1);
        c = index.getX(i + 2);

        _calculateMorphedAttributeData(
          object,
          material,
          positionAttribute,
          morphPosition,
          morphTargetsRelative,
          a, b, c,
          modifiedPosition
        );

        _calculateMorphedAttributeData(
          object,
          material,
          normalAttribute,
          morphNormal,
          morphTargetsRelative,
          a, b, c,
          modifiedNormal
        );

      }

    }

  } else if (positionAttribute !== undefined) {

    // non-indexed buffer geometry

    if (Array.isArray(material)) {

      for (i = 0, il = groups.length; i < il; i++) {

        group = groups[i];
        groupMaterial = material[group.materialIndex];

        start = Math.max(group.start, drawRange.start);
        end = Math.min((group.start + group.count), (drawRange.start + drawRange.count));

        for (j = start, jl = end; j < jl; j += 3) {

          a = j;
          b = j + 1;
          c = j + 2;

          _calculateMorphedAttributeData(
            object,
            groupMaterial,
            positionAttribute,
            morphPosition,
            morphTargetsRelative,
            a, b, c,
            modifiedPosition
          );

          _calculateMorphedAttributeData(
            object,
            groupMaterial,
            normalAttribute,
            morphNormal,
            morphTargetsRelative,
            a, b, c,
            modifiedNormal
          );

        }

      }

    } else {

      start = Math.max(0, drawRange.start);
      end = Math.min(positionAttribute.count, (drawRange.start + drawRange.count));

      for (i = start, il = end; i < il; i += 3) {

        a = i;
        b = i + 1;
        c = i + 2;

        _calculateMorphedAttributeData(
          object,
          material,
          positionAttribute,
          morphPosition,
          morphTargetsRelative,
          a, b, c,
          modifiedPosition
        );

        _calculateMorphedAttributeData(
          object,
          material,
          normalAttribute,
          morphNormal,
          morphTargetsRelative,
          a, b, c,
          modifiedNormal
        );

      }

    }

  }

  const morphedPositionAttribute = new Float32BufferAttribute(modifiedPosition, 3);
  const morphedNormalAttribute = new Float32BufferAttribute(modifiedNormal, 3);

  return {

    positionAttribute: positionAttribute,
    normalAttribute: normalAttribute,
    morphedPositionAttribute: morphedPositionAttribute,
    morphedNormalAttribute: morphedNormalAttribute

  };

}


export {
  computeTangents,
  mergeBufferGeometries,
  mergeBufferAttributes,
  interleaveAttributes,
  estimateBytesUsed,
  mergeVertices,
  toTrianglesDrawMode,
  computeMorphedAttributes,
};
